Find Your Pump
A free solar water pump sizing calculator: pick your state, describe your water source, lift and daily need — and get the Dankoff surface pump sized for your system.
Find your pump in five steps
Tell us where you are, where the water comes from, and how much you need each day. We match it against the published performance of every Dankoff Solar surface pump and point you to the right model.
- 1Location
- 2Water source
- 3Lift & distance
- 4Water need
- 5Your pump
How the sizing calculator works
Unlike a black-box quote form, this calculator shows its math — the same method our engineers have used to size solar pumping systems since 1983:
- 01
Flow needed
Daily gallons ÷ peak sun hours
Your daily gallons divided by your state’s average peak sun hours: the water a solar-direct pump must move per hour of full sun.
- 02
Total dynamic head
Rise + friction + pressure
Vertical rise, plus friction calculated from the recommended pipe inner diameter and four assumed 90° bends, plus service pressure converted at 2.31 ft per psi.
- 03
The match
Flow + head + source
Both numbers are checked against the published maximum flow, head and suction lift of every Dankoff surface pump, plus dirty-water tolerance. The best match is the smallest pump that covers your need — not the most expensive one.
Want the underlying data?
Solar pump sizing FAQ
Practical answers about flow, sunlight, total dynamic head, suction lift and water quality before you select a pump.
How do I size a solar water pump?
Divide your daily water need in gallons by your location's peak sun hours to get the flow the pump must deliver per hour of full sun. Then add up the total dynamic head: vertical rise plus pipe friction plus any service pressure. Any pump you choose must cover both numbers within its published maximum flow, head and suction lift. The Find Your Pump calculator on this page runs those numbers for you against every Dankoff surface pump.
What is total dynamic head (TDH)?
Total dynamic head is the total resistance a pump must overcome, expressed in feet. It adds vertical rise, pipe friction, fitting losses, and any pressure required at the outlet — each psi of service pressure equals 2.31 ft of head. The finder recommends suction and discharge pipe sizes from Dankoff's Water Pipe Sizing Chart and includes two 90° bends on each side. Dankoff surface pumps cover from 90 ft of TDH (SunCentric) up to 960 ft (SolaRam).
How many peak sun hours does my location get?
In the continental United States, yearly averages range from about 3.9 peak sun hours per day in Washington to 6.5 in Arizona; Alaska averages about 3. A solar-direct pump does most of its work inside that window, which is why the calculator asks for your state before anything else.
Can a surface pump pull water from my well?
Yes, if the water level is within suction reach. Dankoff surface pumps can lift water up to 25 ft vertically at sea level (SolarForce and SolaRam; 20 ft for SlowPump, 10 ft for SunCentric). If your static water level is deeper, the pump can often be placed lower — in a pit or well house — or our design team can advise on the right configuration.
Which Dankoff pump handles dirty pond or river water?
The SunCentric, SolarForce and SolaRam tolerate dirty water, which makes them the choice for open sources like ponds, rivers and irrigation ditches. The SlowPump and FlowLight Booster require clean, filtered water — they are built for wells, tanks and pressurizing applications.
Is the calculator's recommendation checked by an engineer?
Yes. The calculator sizes against yearly-average sun hours and published maximum ratings, which is a solid starting point — and our system design team confirms every sizing free of charge before you buy, including the solar array. Call +1 505-471-3469 or use the contact form.